Thursday, December 23, 2010

..one early autumn morning in 1964, I was sitting in my room in the Sedgwick Museum in Cambridge.. when Toronto's Tuzo Wilson, on sabbatical leave, sauntered in clearly bursting to tell anyone who would listen about his new ideas. He had discovered that I was the new lecturer in structural geology and said: "Dewey, I have discovered a new class of fault." "Rubbish," I said, " we know about the geology and kinematics of every kind of fault known to mankind." Tuzo grinned, and produced a simple colored folded paper version of his now famous ridge/transform/ridge model, and proceeded to open and close, open and close it with that wonderful smile on his face. I was transfixed both by the realization that I was seeing something profoundly new and important, and by the fact that I was talking to a very clever and original man.

Moments like these always enliven a science book and in Krakatoa there is a very satisfying section on the decades long accumulation of observations of gravity anomalies, remnant magnetism, volcanic island chains and faults and ideas on the earth's interior that culminated in the theory of plate tectonics. Tuzo Wilson's discovery that the sense of movement along faults that cut across mid-oceanic ridges is opposite to the then known transcurrent or strike slip faults on land was one such key moment. He had realized that such faults would form if the ocean floor was somehow opening and pushing the split crust in opposite directions. Later observations vindicated his ideas.

Geology is not the only theme of this book. There is much to read about colonial expansion and clashes of the Portuguese and the Dutch both between themselves and with the local Indonesian people. Geology, climate change, trade, cultural and religious evolution before and after the eruption are the narrative threads that Simon Winchester expertly weaves together.

I'm just one third through this book. Its great holiday reading.

I won't be posting now until early next year.. unless off course Anak Krakatoa.. the child of Krakatoa.. the new volcano that is growing at the rate of about 20 feet per year blows up..

Thursday, December 16, 2010

2) The Man Who Killed Pluto - OnPointRadio's Tom Ashbrook talks to astronomer Mike Brown and astrophysicist Neil deGrasse Tyson about why Pluto has been relegated from the league of planets and some other frontiers of astrophysics.

3) Science Sees Further - Ira Flatow of Science Friday talks with Richard Holmes and Sir Martin Rees about the contribution of the Royal Society to science and its history and future.

Dissemination of scientific knowledge for improving public understanding of science with scientists playing the role of advocates and popularizers was a theme that Sir Martin Rees emphasized quite strongly in the talk.

Not long ago scientific societies did not always approve of scientists turned popularizers. Carl Sagan was infamously refused membership of the National Academy of Sciences, some say because of his public profile as a popular science writer and TV personality despite his excellent credentials as a research scientist.

The tide seems to be turning with scientific societies now actively engaging in science outreach in the number of ways.. take for example the recent meeting of the American Geophysical Union where a science blogging workshop and social media meetings are being held for exploring ways to strengthen the scientists connection to the public at large.

That is a good sign. Scientists should be talking more to the public about their work and its significance to society.

Tuesday, December 14, 2010

One of India's great rivers, the Yamuna, leaves the Himalayas and comes rushing on to the plains through a great tear in the Himalayan frontal ranges of the Siwalik mountains.

That breach in the mountains is a dislocation along the Yamuna fault. The sense of movement is left lateral, which means if you are following a rock formation across the fault, you will have to turn left as you cross the fault to trace the same rock formation.

Miocene onwards a thick wedge of fluvial sediments filled up a foreland basin that formed in front of rising thrust sheets uplifted along the active Main Boundary Thrust (MBT). That phase ended about 0.5 to 1 mya.

This fluvial wedge over the last half a million years has been deformed into the Siwalik mountains. These mountains form broad synclines and tight anticlines cut by north dipping thrust faults, a result of the continuing compression of the sediment wedge. The southernmost of these thrusts which brings into tectonic contact the anticlinal Frontal Range of the Siwaliks over the alluvial plains in called the Himalayan Frontal Thrust (HFT).

The HFT is broken into segments and the amount of displacement along these segments or thrust blocks is unequal. For example the blocks west of the Yamuna and east of the Ganga have moved southwards with an opposite sense of movement relative to the central block known as the Dun block. To view this, turn on labels and pan southeastwards in embeddable map below until the town of Haridwar where the Ganga enters the plains.

Thus the Yamuna fault has a left lateral sense of movement while the Ganga fault has a right lateral sense of movement. These faults can be thought of as lateral ramps of the HFT accommodating the displacement caused by the southwards movement of the HFT blocks.

Structural considerations indicate that during the last 0.5 my there has been about 8 km of displacement along the Yamuna and Ganga faults, a slip rate of approx. 16 mm year.

Saturday, December 11, 2010

Disunion Blog has an interesting post by Susan Schulten on how a new map produced by the United States Coast Survey based on the 1860 census helped Lincoln and the public visualize the geography of slavery.

The map was produced with what at that time was a cartographic innovation.. the use of a shaded color ramp to represent ranges in values.. in this case the number of slaves per county in the southern states.

The map reaffirmed the belief of many in the Union that secession was
driven not by a notion of “state rights,” but by the defense of a labor
system. A table at the lower edge of the map measured each state’s slave
population, and contemporaries would have immediately noticed that this
corresponded closely to the order of secession. South Carolina, which
led the rebellion, was one of two states which enslaved a majority of
its population, a fact starkly represented on the map.

Tuesday, December 7, 2010

Models of Deccan volcanism envision that most the lava came out of vents and fissures localized along two major rift zones, the roughly east-west trending Narmada Tapi Satpura rift zone along which today the Narmada and Tapi rivers flow westwards and which initially developed in the Proterozoic but has been active intermittently since and the north-south trending West Coast rift zone which developed during the mid-late Cretaceous as India broke away from Madagascar around 90 mya. There are dyke clusters along these major rift zones and they are thought to be lava feeders, remnants of the pipes through which magma from deep magma chambers was brought up to the surface.

The dykes in the image belong to the Narmada rift zone cluster. They are mostly tholeiitic basalts in composition. Variations in chemical composition shows that the Deccan lava pile was built up through several major eruptive episodes. A comparison of this dyke cluster suggests that many of these dykes were likely feeders to the older and middle eruptive phases of the lave pile, although a feeder relationship with a lava flow is rarely seen in the field.

Saturday, December 4, 2010

Friday, December 3, 2010

Nature News has a fascinating article by Lizzie Buchen on human ecology... not the ecology outside and around us - but the ecology within - on which a variety of microbiota flourish.

That variety is now under scrutiny...as scientists try to understand the linkages between the types of microbiota living inside us and our health. Establishing those linkages to the point where they could be of clinical value is a long way off but the efforts are bringing together unusual collaborations like the one where Jillian Banfield an expert on the microbiota of acid mines..the so called extremophiles.. is teaming up with Michael Morowitz and David Relman who are working on the microbiota in the intestines of premature infants.

...the connection...?

"The scientific questions are really cross-cutting," says Banfield. One
example, she says, is colonization — which organisms arrive first and
how the community evolves (see 'Baby's first bacteria').
"It's ecological succession," Banfield says. "If you look at the
surface of a pool of acid mine drainage and imagine the first organisms
to arrive, it's the same as imagining a newborn baby with a sterile GI
tract, and the first organisms there."

Plus, Dr. Banfield has experience sequencing and analyzing DNA from the microbes of acid mines where there are only a limited number of microorganisms. The infants intestine is similarly an ecosystem which has been recently colonized by only a few microbes, which makes it that much easier to categorize them using Dr. Banfield's techniques.

The article has a lot more on the emerging field of the human microbiome..it was an eye opener for me... in sheer number of cells we are 99% microbial...

Thursday, December 2, 2010

Just a pointer that GeoCommons, a public domain web mapping application by Fortiusone Inc has a growing collection of geology and natural resources data.

I've been having fun last couple of days downloading some U.S. water use datasets, importing them in Manifold GIS, making them map ready and then uploading them back on Geocommons. Using the Map Maker I have then presented the results in a couple of maps.

The first shows the total ground water usage by state in millions of gallons per day (colored states) and also ground water use as percent of total water use (graduated dots). Orange blocks as urban centres with population greater than fifty thousand. You can see the east west divide in water use type. The east relies a lot more on surface water. The central and western areas along with Florida in the south east rely on ground water more than the eastern states. The importance of the Ogallala or High Plains Aquifer is clearly seen in the central states as is the importance of the Central Valley Aquifer in California.

You can drill down and bring out other dimensions of this data. For example in the map below I've plotted one of these dimensions, the ground water usage for irrigation in millions of gallons per day in the High Plains counties. The High Plains Aquifer is outlined.

This is not a full "cloud GIS" yet in terms of users borrowing or leasing the full range of GIS functionality from a remote computer. I had to follow a hybrid approach as did other data donors in terms of using a personal GIS to process the data to certain specifications before uploading it to this online service. Still such services are gaining importance and functionality and they give users who don't own software an inexpensive tool to actively engage with spatial data.

Tuesday, November 30, 2010

I'm experimenting with a new series. The idea is to put up a satellite image of an interesting geological feature from India along with a brief explanation. I'm going into this without much preparation. I have about 5 locations ready but will have to actively look for more features to put up.

Which imaging service should I use? Google Maps and Bing Maps are the easily accessible choices, but in honor of India's Remote Sensing Program which has been a credit to the country, wherever possible I will be putting up an image from an Indian Remote Sensing Satellite as well. I'm going to be using the public domain web mapping service Bhuvan as the source of the images taken from Indian satellites. The resolution allowed for unrestricted use of imagery via services like Bhuvan is a maximum of 5.8 meters, and so I will supplement that with an embeddable Google Maps frame for higher resolution images and a more interactive experience.

The inaugural image is a sentimental choice from my first solo mapping project in the Proterozoic Cuddapah Basin of Andhra Pradesh, south India, located between the towns of Kurnool and Nandyal.

The feature is an ENE plunging asymmetric anticline with spectacular dip slopes of quartz arenites making up the southern limb of the fold and left-lateral movement along a regional fault steepening the northern limb of the fold. There is some copper mineralization along the fault. The Cuddapah basin is an intra-cratonic basin which was filled up in several depositional mega cycles. Sections of two of these mega cycles are exposed in this area. The older mega cycle comprising the Cuddapah subgroup is exposed in the core of the anticline. An angular unconformity separates the older cycle from the younger Kurnool cycle (sub group) which is exposed along the limbs.

Thursday, November 25, 2010

via Geology.com, the USGS has released a pretty useful primer on the geology of Rare Earth elements. The types of host rocks are described along with the challenges of mineral processing for element extraction.

A table summarizes the host rock types along with examples of their occurrence. ... a bit surprised that no examples from India have been given. There is active mining in India of placer sand type deposits from the coasts of Kerala. These sands are rich in monazite a phosphate derived from granitic rocks which has been used as a source of Thorium but is increasingly now gaining importance as a source of Rare Earths too. Inland placers have also been identified as potential sources.

There are two other potential geological sources of Rare Earths in India. Alkali and carbonatite intrusives and volcanic flows. These broadly fall in two age groups; through the Proterozoic, developed during episodic magmatic events. Tamil Nadu and Rajasthan carbonatites are well known but their Rare Earth potential needs to be evaluated in detail. The younger ones are late Cretaceous in age, related to the Deccan volcanic episodes and are located in the western regions around Gujarat.

The third potential source of Rare Earths are the thick residual clay and lateritic soils developed on granitic source rocks. These types of deposits are being exploited in south China. Such soils are present through the western parts of south India. They formed during intense weathering of Precambrian terrains during the Cenozoic. I am not sure how well they have been characterized in terms of their Rare Earth element concentrations.

Even if they are recognized as a resource, it will be tough to exploit them. Most of these thick soils are covered with tea and coffee plantations... a mighty industry of its own.

Monday, November 22, 2010

The Times of India Sunday Pune Edition (Nov 21) carried a good article (the print edition has a more detailed write up) by Dipannita Das on the ecological importance of the rocky plateau landforms of the Western Ghats. These outcrops are often termed "wastelands", a terminology that reflects classification of landscapes by their economic potential, a classification tradition that goes back to the days of the British Raj. Rocky plateaus were thought to be unproductive and were termed wastelands.

Here is a classic example of one of these rocky plateaus from Panchgani, a hill station south of Mumbai. The cap is made up of an early Cenozoic laterite. At other locations the plateaus are hard basalt flows.

And here is a view of the surface of such plateaus.

It may seem mostly barren, but as the article details, such plateau environs are teeming with plant and animal life, specialized to live in crevices and along the slopes and depressions and hollows and water seeps that have formed by the action of physical and chemical weathering.

There is a national level effort going on to map the biodiversity of the Western Ghats (see site WesternGhatsIndia.. not working at the time of writing ) and one hopes that many of these ecologically rich and interesting rocky plateaus will be afforded protection from various anthropogenic activities. These plateaus are of geological importance too. As I wrote in an earlier post, many of these "rocky" surfaces tell a story of the erosional, uplift and weathering history of the Western Ghats.

Over the last couple of years I have come across increasing number of reports in newspapers on various environmental issues. Reporters are talking not just to a few well known and politically connected scientists, but also to faculty and researchers from local colleges and institutes that are on the front line ... doing field work, collecting data and conducting research on various biological and geological aspects of the surrounding landscapes.

That marks a positive change in terms of increased science outreach by the media and raising awareness of these issues in the communities that are going to be directly affected by the unplanned development of the nearby environment.

I went hiking in the Mukteshwar area of the Kumaun Himalayas and promised I would be posting some geological maps and cross sections and so here goes.

If you are a field geologist looking for some classic fold belt structures to map you are not going to be over excited if you are restricted to the Mukteshwar area. The outcrop geology given the contorted and complex standards of portions of the Himalayas is quite sedate.

The entire region is made up of a NE steeply dipping block of phyllites, quartzites and mica garnet schists. Great exposures are few due to the lush vegetation. The one on the left are mica-garnet schists and quartzites forming an escarpment which is used for rappelling and rock climbing.

Along road cuts like the one below you do get a good view of the quartzites and schists. This one contains elongate deformed quartz veins.

These north east dipping strata are one limb of a regional synform. The cross section below depicts the internal geology of the synform made up of a sequence of medium to high grade metamorphic rocks intruded by granites. All the thrust faults shown in the cross sections are thought to sole in to the Main Central Thrust. The interpretation is that the Main Central Thrust has splayed or split into these subsidiary faults. I'll explain the role of the Main Central Thrust a little later in the post. My location was close to the label Study Area.

The larger geological context within which this quartzite-schist terrain stands is quite interesting.

As I mentioned Mukteshwar falls in what is known as the Lesser or Lower Himalayas. Below I've put up a topographic profile across the Kumaun Himalayas. SH - Sub Himalays, LH - Lower/Lesser Himalayas, HH- High Himalayas , ITS - Indus Tsangpo Suture beyond which is the Tibetan plateau.

Early mapping in some areas indicated that these physiographic divisions also corresponded with 4 different geological domains which were in tectonic contact along great thrust faults.

So, the Sub Himalayas or Siwaliks are made up of Cenozoic foreland basin sediments separated from the Gangetic alluvium by the Himalayan frontal thrust and from the Lower Himalayas by the Main Boundary Thrust.

The Lower Himalayas in turn are made up of unmetamorphosed to low grade metamorphic mid-late Proterozoic Indian basement (Lesser Himalayan sequence) separated from the High Himalayas by the Main Central Thrust.

And the High Himalayas are made up of high grade metamorphic mid late Proterozoic Indian basement (Greater Himalayan Crystalline sequence) along with unmetamorphosed Paleozoic sediments (Tethyan Himalayan sequence) and this terrain meets the Asian plate along the Indus Tsangpo suture, the zone of plate collision.

The simplified story is that as the Indian continental crust collided with the Asian crust, the Indian plate buckled, deformed and broke up perhaps along pre-existing zones of weaknesses in the Indian crust. These breakages evolved into the major thrust faults bringing into structural contact different geological terrains. The gradient of compressive forces and vertical uplift increases from SW to NE imposing a conformity between the physiographic and geological divisions.

Physiography and geology do coincide in regions like central Nepal but the correspondence between the physiography and geology does not hold up everywhere. For example the Almora /Mukteshwar area which falls in the physiographic Lower/Lesser Himalayas has exposures of very high grade rocks corresponding to the Greater Himalayan crystalline sequence normally found in the physiographic Higher Himalayas.

Below is a map of the Himalayan orogen. I was located just east of cross section C in the Almora-Dadheldura nappe.

Nappes are terrains which have moved some distance along thrust faults. In this case the Main Central Thrust has moved the Greater Himalayan crystalline terrain over the Lesser Himalayan sequence along a nearly flat or low angle thrust. During continued orogenic forces the continental crust kept buckling, resulting in the Greater Himalayan crystalline terrain along with the Main Central Thrust in this region becoming folded into a broad synform and antiform. Erosion has removed the antiform leaving exposures of the Greater Himalayan crystalline sequence stranded on top of the Lesser Himalayan sequence- cut off from its root in the Higher Himalayas.

This is how high grade metamorphic rocks of the Great Himalayan crystalline sequence and sediments of the Paleozoic Tethyan sequence which make up the High Himalayas are in many regions exposed in the Lower Himalayas.

They are erosional remnants of thrust sheets.

Cross section C below is a depiction of this scenario. The pink is the Greater Himalayan crystalline sequence, the pale brown is the Lesser Himalayan sequence and the blue is the Tethyan Himalayan sequence. MCT is the Main Central Thrust. The red arrow indicates my approximate location within this synform.

Such blocks of the nappe isolated from its root terrain are called klippen. The Almora /Mukteshwar area high grade crystalline rocks are part of a klippen surrounded by unmetamorphosed to low grade Lesser Himalayan sequence.

This is the consensus view.... put forward after decades of mapping and dating rocks in this region. The movement of the thrust sheets and the erosional formation of klippen according to this view took place in the mid Miocene, synchronous with a major uplift and deformation phase of the Himalayas. Another view is that the rocks of the Almora-Mukteshwar area are not allocthonous or transported from elsewhere but are authocthonous i.e. they are a rooted part of the Lesser Himalayan sequence, the different grades of metamorphism reflecting local metamorphic gradients.

You don't really get a feel for this larger picture if you are hiking within a small area as I was. Still it was pretty awesome thought, that I was standing on a klippen whose root lay in the High Himalayas some 75 km away in front of me.

Saturday, November 13, 2010

Pune has several hills scattered throughout its extents. About 1600 odd hectares of them going by the various sources. Some of the hill land is owned by government and is managed by the forest department, some is government owned and is covered by slums and some is under private ownership.

There is a grand plan to convert all or most of this 1600 odd hectares into bio-diversity parks. While the idea of setting aside large swaths of hills as open spaces is creditable, reporting by the media on the supposed benefits of these parks verges on the side of being silly.

Here are a couple of examples I see again and again in media reports on this issue, most recently in yesterday's Times of India (Nov 12 2010, Pune edition):

Air pollution in Pune is a threat to health and well being. The United Nations recommends at least 12 sq m of green area per person for adequate environment for physical and mental health.

An average family of five will require 60 sq m of green area to survive and breathe. Once it comes up, the BDP's will provide clean air for approximately 35 lakh people.

BDP's are the bio-diversity parks and 35 lakhs equals 3.5 million.

Reading this strange environmental calculus makes me wonder how people in Tokyo, Hong Kong, Dubai and Las Vegas, cities with either hyper dense populations or ones bereft of any greenery manage to live healthy lives.

Going by the U.N criteria as presented in the Times of India (TOI) all the people in these cities should be diseased wrecks by now.

The fact is that the greening of the hills will not make a dent in either offsetting carbon dioxide emissions or preventing other types of air pollutants. Pune by a rough estimation of the number of vehicles (approaching 2 million) likely emits more than a million tons of carbon dioxide a year from vehicles alone (here is another estimate). There are other sources that add to this.

1600 hectares of the Utopian forest that may or may not come up on these hills will sequester at most a few thousand tons of carbon dioxide per year. That is the best case scenario. Most likely the number will be disappointingly smaller. Currently the forest on these hills sequester a few tens of tons per year according to this study on carbon sequestration in Pune.

Besides trees don't suck in particulate matter and sulfur and nitrous compounds which have ill effects on health. More than CO2, these pollutants pose an immediate threat to our health. These continue to be emitted in large quantities mostly as vehicular emissions and tree plantations won't reduce their presence in the air above Pune.

I would like to see at least parts of these hills being left as open spaces..there are clear benefits in terms of providing cool recreational spaces for citizens and as a refuge for the urban bird and animal populations. But whether those hills are left barren or are built upon or are completely covered by trees won't make a difference in terms of providing clean air to the city.

That will happen only through cleaner and more efficient use of energy sources particularly a move towards cleaner vehicular fuels.

Monday, November 8, 2010

This one I could not pass on and it gives me a chance to nitpick about reporting on evolution :)

The Zoque people of southern Mexico pray to the rain gods every year by releasing a leaf-bound paste made of lime and the ground-up root of the barbasco plant in to cave waters. This mixture is a natural fish toxin.

Researchers from Oklahoma State Univ. and Texas A and M found out that fish populations exposed to this poison have evolved a resistance to it over centuries.

However, a team of researchers led by Dr. Michael Tobler, an
evolutionary ecologist at Oklahoma State University, and Dr. Gil
Rosenthal, a biology professor at Texas A&M, has discovered that
some of these fish have managed not only to develop a resistance to the
plant's powerful toxin, but also to pass on their tolerant genes to
their offspring, enabling them to survive in the face of otherwise
certain death for their non-evolved brethren.

The use of the phrase ....these fish have managed not only to develop a resistance.. may be read by many who are not familiar how evolution works to mean that some individual fish over their lifetimes develop a physiological resistance to the poison and then pass on that trait to their offspring.

That is inheritance of acquired characteristics and that is not how evolution by natural selection works. Rather some fish within a population will by chance happen to have genes that confer some resistance to the poison. These individuals will leave behind more descendants than individuals who don't possess that version of the gene. Over time the poison tolerant gene will become more common in the population.

The press release does better later in the article:

Mollies able to tolerate the poisonous conditions survived and passed
those traits to their offspring, resigning those that perished to their
fate of serving as a ceremonial feast for the Zoque.

The two came out meaning different things to me in terms of how evolution works... the second paragraph sounds more accurate.

Link to paper: An indigenous religious ritual selects for resistance to a toxicant in a livebearing fish. Biology Letters, 2010; DOI: 10.1098/rsbl.2010.0663

Wednesday, November 3, 2010

As the Indian continental block ploughed northwards and approached Asia starting earliest Cenozoic, when did the sea between the two continents disappear. When did the two continents become one, when did the first "land bridges" between the two continents develop.

Last week's post about early Eocene insect fossils preserved in amber from the Cambay shale in western India prompted these questions. The insects show similarities to Cenozoic insect fauna from Europe, Asia and Australiasia.

Although similarities between insect fauna imply faunal exchanges between continents they may not necessarily indicate that the two continents were connected by land bridges. Insects can survive on rafts for long periods and favorable ocean currents and island chains in the ocean between the two continents may have provided sufficient stepping stones for insect trans-continental migration.

Two types of evidence speak more directly to the presence of land bridges. One is the first appearance of distinctly Indian mammals on the Asia plate and vice versa. Mammals would have needed a solid connection between the two continents to migrate.

Another type of direct evidence is the presence of terrestrial sediments in the zone of collision. As the two continents collided, there would have been the development of complex topographic in the zone of collision. High thrust mountains but also regions which sagged and became basins. Of interest are basins which were filled with lakes or became courses for rivers.

The presence of lacustrine or fluvial sediments resting on rocks of the Indian plate but containing grains which show the provenance or source to be rocks of the Asian plate is strong evidence that the two continents had sutured into one and rivers originating on one plate were transporting sediments and depositing them on the other, i.e. land bridges had formed between the two.

There are at least two other indirect ways of inferring land bridges. One is the reduction in plate velocity. The moving Indian plate had set a Cretaceous record for speed but abruptly slowed in the earlier Cenozoic. That implies that continental crust was meeting resistance from another continental block and the two continents were suturing.

The other indirect way is to look at the metamorphism of continental crust. As the continents collided, continental crust was transported to depth and transformed into a suite of metamorphic minerals at high temperatures and pressures. The timing of these metamorphic events speak to the coming together of continents.... so do the presence of intrusive granites which formed by melting of the continental crust during the collision.

We know from all these above types of evidence that the collisions began in early Eocene and it was not uniform and simultaneous across the present length of the Himalayas. The western edge of the Indian plate met first and the continents sutured eastwards through the Cenozoic.

Wednesday, October 27, 2010

This story is being covered by a number of science news outlets. Science Daily covers it here. The link to the paper in PNAS is here.

Cambay basin in which these fossils were found is a cratonic rift basin that formed beginning mid-late Cretaceous as India broke away from Africa and then Madagascar and finally from Seychelles. The fossils have been found in near shore deposits rich in lignite and shale which contains fossil wood as well. The graphic below shows the configuration of continents in early Cretaceous.

The Cambay basin formed along the eastern continental margin of the evolving Indian continent, its orientation following ancient Precambrian mobile belt trends, ancient weak zones of the crust along which fragments of Gondwanaland broke. The figure below shows the position of the Cambay basin among other Indian sedimentary basins.

After its breakup from Gondwanaland the Indian subcontinent drifted
northeastwards as a seemingly isolated block for tens of millions of
years until it slammed into Asia, initial contact beginning perhaps around 50
million years or so.

The preserved insect fossils date from a time just before or at the beginning of contact between India and Asia when there would have been island chains or perhaps the first land bridges between the two continents. They don't show similarities with fauna of Madagascar or Africa the two fragments of Gondwana that India most recently broke away from. Instead they show similarities with fauna from the Eocene in N. Europe, Asia, to recent Australiaasia and the Miocene to recent of Americas suggesting faunal exchange between these continents by early Cenozoic times.

Perhaps oceanic currents were favorable in bringing flotsam and jetsam to Indian shores from these continents and along with it an exchange of insect passengers. The faunal similarities from this time period between India and other continents though might be restricted to small animals like insects which could perhaps survive long journeys on rafts. Interesting to speculate whether larger animals groups like reptiles and early mammals from India show some degree of Cretaceous and Early Cenozoic endemism.

The amber in which these fossils insects are entombed has been shown to be chemically similar to Dipterocarpaceae, a family of hardwood trees, implying that these types of broad leaf forests were present during the early Eocene and evolved perhaps even earlier.

The Early Cenozoic was a period of global warm climate and the evolutionary radiation of several groups of social insects took place during this time. The variety of insect fossils preserved in the Cambay shale reflects this diversification.

Tuesday, October 26, 2010

In an interview on Fresh Air, Richards recounts how he woke
up just long enough to record the famous opening riff of "Satisfaction"
on a cassette player he'd placed next to his bed.

"I
go to bed as usual with my guitar, and I wake up the next morning, and I
see that the tape is run to the very end," Richards tells Terry Gross.
"And I think, 'Well, I didn't do anything. Maybe I hit a button when I
was asleep.' So I put it back to the beginning and pushed play and
there, in some sort of ghostly version, is [the opening lines to
'Satisfaction']. It was a whole verse of it. And after that, there's 40
minutes of me snoring. But there's the song in its embryo, and I
actually dreamt the damned thing."

Einstein had dreamy thoughts about the relativistic nature of space-time. Keith Richards dreamt up the most famous guitar riff in rock and roll.

Monday, October 25, 2010

I am back after several days of hiking in the Mukteshwar area of Uttarakhand. I'll be writing a more geology oriented post in a few days but let me first put up a few photos to give you an idea about the place.

It was beautiful.. there is no other word to describe it.. take a look.

Tuesday, October 12, 2010

I'll be of the radar for the next couple of weeks or so. First to Delhi for some work and then off to Mukteshwar, a small temple town in the Kumaon region of the Himalayas for a few days of hiking and recreation.

Mukteshwar falls in what is known as the Lesser Himalayas. As the name suggest it reflects the physiography of the region as compared to the Greater Himalayas. Overall the Lesser Himalayas as not as rugged and high as the Greater Himalayas. There are geological differences as well.

I've put below a rough sketch of the major litho-tectonic provinces of the Himalayan orogen. These represent the roughly WNW-ESE trending deformed blocks of the Indian plate as the Indian shelf broke up along major faults during the India-Asia collision.

From Delhi I'll be traveling on the Quaternary alluvium until I cross the Himalayan frontal thrust which brings into contact the Quaternary alluvium with the Neogene Siwalik mountains - remnants of the Cenozoic foreland basin that formed in front of the rising Himalayas.

I will then cross the Main Boundary Thrust, which places the Lesser Himalayas over the Siwaliks. The Lesser Himalayas are made up of Proterozoic to Paleozoic rocks (geological division - the Lesser Himalayan sequence) and represent the basement and metamorphosed cover of the Indian shelf. Beyond that in thrust contact along the Main Central Thrust are the Greater Himalayas which are also made up of the Proterozoic basement and Paleozoic metamorphosed cover of the Indian shelf (geological division -Greater Himalayan crystalline complex).

The Greater Himalayas are generally of higher metamorphic grade and may represent the exhumation of a deeper crustal level.

Beyond that.. tectonically juxtaposed with the Greater Himalayas along the South Tibetan Detachment are the Tethyan Himalayas which are composed of mostly unmetamorphosed Paleozoic to Eocene sedimentary cover deposited on the Indian shelf. Beyond that is the zone of collision known as the Indus-Tsangpo suture and beyond that .... the Asian plate.

I've been able to draw only the Himalayan Frontal Thrust and the Main Boundary Thrust with some confidence. I am not well versed enough to pick out the other boundaries between the provinces from a satellite image. But I think I've got the general placement of the provinces correct.

As I mentioned, Mukteshwar falls in the physio-graphic province of the Lesser Himalayas.... but geologically..?

I'll write about it in more detail with some maps and cross sections when I return. There is somewhat of a surprise regarding the geology and structure around Mukteshwar.

The night train from Delhi will put me in the Siwalik foothills by dawn. Its an early morning drive from there up to Mukteshwar which is at an altitude of around 7200 feet.

I hope to catch the sunrise as I drive up the Cenozoic alluvial fans that make up the Siwaliks and cross over into the Proterozoic metasediments of the Lesser Himalayas...

Wednesday, October 6, 2010

On Point Radio invites geologist Anthony Mariano to talk about rare earth elements, their geological distribution and applications and why China currently dominates the rare earth market.

Very briefly... China dominates because of cheap labor and a willingness until of late to tolerate environmental degradation that accompanies mining and processing of rare earth deposits... but listen to the talk for details of how this came to be.

Christine Parthemore, the other guest talks on U.S. national security and policy implications of China's rare earth market domination.

The geological context of these deposits in China varies depending on geography. The inner Mongolia deposits are within carbonatite like bodies and veins that are intrusive and replace dolomites and shales (see here and here). In southern China the rare earths occur as ions adsorbed on clays, which are a weathered residual deposit derived from a mostly granitic source.

Monday, October 4, 2010

The Indian Space Research Organization has released a new beta version of Bhuvan a web mapping tool which serves images of India and the rest of the world taken from various Indian remote sensing satellites. It is available in 2D and 3D versions.

The new versions looks a little slicker and cleaner than its predecessor. But 5.8 meters is the highest resolution imagery available via Bhuvan while Google Maps and Google Earth both have long started serving 1 meter or so images of Indian cities and hinterland.

Government prescribes the following guidelines to be adopted for dissemination of satellite remote sensing data in India:

All data of resolutions up to 5.8 m shall be distributed on a nondiscriminatory basis and on “as requested basis”.

With a view to protect national security interests, all data of 5.8 m and better than 5.8 m resolution images will be screened by the appropriate agency before distribution so that images of sensitive areas are excluded.a. Data of 5.8m and up to 1m resolution can be distributed to users after screening and ensuring that the sensitive areas are excluded.

b. Data of 1m resolution and better will also be screened as above and the following procedure will be followed for its distribution.i. Government users can obtain the data without any further clearance.ii. Private sector agencies, recommended by at least one Government agency for use of 1 m and better resolution data for supporting development activities, can obtain it without any further clearance.iii. Private, foreign and other users can obtain the data after further clearance from an inter-agency High Resolution Image Clearance Committee (HRC).iv. Specific requests for data of sensitive areas, by any user, can be distributed only after obtaining clearance from HRC.v. Specific sale/non-disclosure agreements to be concluded between NRSC and users for data of 1 m resolution and better.

What this means is that under the current policy scenario, high resolution (1 meter or so) images collected from Indian satellites will not be available via open access free web mapping tools like Bhuvan. The only users of this high res imagery will be those who have obtained clearances for images of pre-defined geographic extent to be viewed in specialized GIS and Remote Sensing software.

This will severely limit the user base of Bhuvan and Indian imagery:

For example-

1) That means despite a developer API for Bhuvan being available there will likely be few takers especially for designers of urban applications.

2) And Bhuvan for the mobile market?... all those location apps, business listings, navigation already available via Google..?... forget it.. can't be done when your street and neighborhood looks like an undifferentiated granular blob.

Tuesday, September 28, 2010

The Deccan Volcanic Province in best known as a thick pile of basalt lava. It is igneous rock country. In Maharashtra, the plateau east of the western ghats is drained by rivers small and big flowing ultimately into the Bay of Bengal. Many of these rivers originate in the very humid mountainous region known as the western ghats. Eastwards in the more arid climatic zone prevailing over the plateau these rivers have deposited a lot of sediment throughout the Quaternary and possibly earlier.

I was visiting a mineral museum north of the town of Sangamner a couple of weeks ago and came across some superbly preserved fluvial bedforms along a road cut just south of Sangamner. Fluvial bedforms are sedimentary structures formed as sediment is moved and is deposited by current action in the river bed. If you zoom and pan southwards along National Highway 50 south of Sangamner in the embedded image below you can see a trace of a small tributary of the river Pravara.

View Larger Map
The sediments in the images below were deposited by that tributary. The river has incised or cut into its own deposits and the active channel today is about 10-15 meters below the section seen in the images. So these deposits form an ancient probably late Pleistocene fluvial terrace a few hundred meters wide.

1) View of fluvial bedforms with pebbly and sandy planar and cross stratification clearly seen. At right center is a pebbly cross bedded wedge, possibly a point bar deposit. So, the sediment you see was being rolled along the bed of the river. The morphology of the sediment surface was like a sheet of sand and pebbles (the planar layers are a cross section of these sheets). Here and there the sediment sheet was wrinkled into large waves (the large cross beds are likely the cross section of these large wave forms). Some sediment was being deposited along the banks along inclined surfaces forming the point bar deposits.

2) Another wide view of planar and cross beds.

3) Shallow cut and fill structures. These are common features in the river bed as pulses of high energy events such as floods may scour the sand in the river bed and then fill up the trough formed by sediment.

4) A small channel filled by gravel and sand overlain by planar and cross bedded sand and pebbly layers.

I couldn't stay long at the outcrop as traffic was zooming perilously close to me and we had to go some distance. These deposits though have been interpreted to preserve a record of Quaternary climate change. The entire section records a phase of mid-late Pleistocene - early Holocene aggradation in which sediment was deposited and the river channel built upwards. This was followed by a phase of incision later in the Holocene when the river cut into its own deposits leaving stranded terraces.

I hope this outcrop survives for long. Apart from aiding our understanding of fluvial geomorphology and climate change it is a superb teaching tool for sedimentary geology and geomorphology classes. Unfortunately intensive farming activity and excavations for construction are slowly degrading these fluvial deposits near Sangamner.

Tuesday, September 21, 2010

I had to take the pictures from behind a glass pane so excuse the lack of extreme close ups.

Take a stab at identifying the minerals and post your answers in the comments. I will put up the correct answers in this post in a few days.

Update: Answers at the bottom.

A)

B)

C)

These palm sized samples were selling in the range of Rs 5000 to Rs 10,000 (~ $100 to $200). Larger samples were in the range of Rs 25,000 to Rs 60,000. These are prices for the Indian market. I imagine there will be a significant markup for sale in the U.S and Europe, Japan etc.

Gap along the Himalayan axis where high heat flow is associated with granitic intrusives is because the geothermal potential of Nepal is not shown. Within peninsular India all the high heat flow regimes fall along either old Precambrian weak zones which have been reactivated during late Paleozoic -Mesozoic rifting events or coincide with the evolution of the western margin of India during Mesozoic rifting from Africa /Madagascar / Seychelles. This rifting resulted in lithosphere stretching and thinning and hot mantle upwelling.

The focus in India has been on conventional geothermal energy exploration in the vicinity of volcanoes, geysers and hot springs where high heat flow occurs at shallow depths of a few hundred meters. These projects use naturally occurring steam and hot water to generate electricity. The estimate is that these shallow heat flow sites could potentially generate up to 10,300 MW of electricity. Engineered geothermal systems (EGS) projects in which water is circulated along drilled pathways to great depths to heat it up can be located in areas of relatively low heat flow. EGS have not yet been explored in any detail in India. These projects are more expensive but because they don't have to be located near unusually high heat regimes the aggregate energy potential may be even bigger than what is estimated for conventional projects.

Everything right now is still in the "estimates and potential" stage. Not much energy if any at all is being produced from any of these sites. So far at least the government has been neglecting this clean energy resource. We lack the right policies to make both conventional and engineered geothermal energy economically viable.

Thursday, September 16, 2010

T.N Narasimhan writes a short correspondence in the latest issue of Current Science on the comparatively lesser importance given in India to earth sciences as compared to math, physics and chemistry.

The reasons as to why earth system science is considered a poor relative of the other sciences in India may be many and complex. Among these, the following two appear credible. First is the populist perception that mathematics, physics and chemistry demand highest levels of intelligence. The second is a more mundane reason of jobs, financial security and career opportunities. Currently India is pursuing a hope of economic growth based on physical and biological technologies, and entrepreneurship. Not surprisingly, India’s best young talents have little inclination to pursue earth sciences. However, it seems likely that India’s economic expectations may be seriously jeopardized if earth sciences continues to be a poor relative of the other sciences, and the country fails to nourish excellence in earth sciences as a means of sustainable management of water, land, ecosystems and the environment.

I don't disagree except that career opportunities have been improving recently with the entry of private operators in the oil and mining industries. So the earlier perception that geology = constricting government job is slowly going away.

Tuesday, September 14, 2010

Nature News has an article by Jane Qiu detailing an ambitious drilling project ultimately aimed at recovering 10 km of core from a Cretaceous sedimentary section deposited in the Songlia Basin, northeast China. The Songlia basin is a rift basin that saw establishment of very long lived lakes fed by rivers throughout the Cretaceous, a geological period which saw great fluctuations in temperature, atmospheric carbon dioxide and sea / lake levels. Much of our understanding of the Cretaceous comes from marine sediments. Scientists have started analyzing portions of a two km core of terrestrial sediment in the hope of understanding how dramatic shifts in temperature and CO2 content affected conditions on land.

Here is an interesting bit:

Other as-yet-unpublished results also point to a possible position for the K/Pg boundary. But it is about 100 meters below the depth determined by Wan Xiaoqiao, a palaeontologist at the Beijing-based China University of Geosciences who used fossils of spores, pollen, phytoplankton and ostracod to locate the boundary. The researchers are trying to determine why the estimates differ, and to nail the boundary down to 2–3 metres, so that detailed geochemical analysis can be performed to look for rare elements, such as iridium, that are common in meteorites and were spread around the globe by the cosmic impact.

The article doesn't say how the K/Pg boundary has been identified but one cannot help speculating on a topic like the end Cretaceous mass extinction.

Some scenarios:

1) The boundary has been incorrectly located and more detailed work will place it near the palaeontologically determined K/Pg boundary.

2) The physical location of the K/Pg boundary is correct and more detailed studies will show that it temporally coincides with the palaeontological boundary. This will imply that the intervening 100 meter or so of sediment was deposited very rapidly.

3) The identified boundary is indeed an event pointing to a large environmental perturbation caused by a meteorite impact but palaeontological evidence for a mass extinction occurs a considerable amount of time after this event as evidence in the 100 meter or so of intervening sediment will tell us. This is a scenario similar to what Gerta Keller and colleagues have been arguing using late Cretaceous sections from Texas and near the Chicxulub impact site i.e. the Chicxulub impact took place a few hundred thousand years before the mass extinction.

This might turn out to be an important section in the context of the mass extinction debate. Cretaceous geology is never dull.

Tuesday, September 7, 2010

Yesterday night I caught a Discovery channel program on earthquake monitoring along the San Andreas Fault. A short segment discussed the San Andreas Observatory At Depth a joint effort involving the International Continental Drilling Program (ICDP), NSF and the U.S. Geological Survey (USGS) which involves drilling, recovering core from the fault zone and monitoring seismic activity at a depth of around 3 km or so to better understand the stresses along the fault.

The Indian government has an even more ambitious plan. There is news that a drilling project is being planned along the Koyna fault in southern Maharashtra that will go as deep as 8 km, a hole that will penetrate through the 2 km thick Deccan lava pile and into the underlying Archaean-Proterozoic basement.

The Koyna region has been a locus of seismic activity of > 5 magnitude, the largest being the 6.3 magnitude earthquake of 1967. It is also considered to be one of the better known examples of Reservoir Triggered Sesimicity, the culprit being the Koyna hydroelectric dam.

The map below shows the Koyna fault, which is hypothesized to be an extension of a late Archean -Early Proterozoic shear zone or a zone of weakened crust situated within the Dharwar craton, an Archean continental nuclei. Accumulating stresses along this shear zone periodically break the crust. Another theory is that the Koyna fault coincides with a very deep basement fault oriented roughly with the Western Ghat scarp and is perhaps related to the Mesozoic rifting of India and Cenozoic uplift of the Western Ghat region. The two theories are not mutually exclusive.

The ultimate reason why the Indian crust today is under stress is believed to be the compressional forces generated by the Indian plate colliding with Asia beginning early Cenozoic. These forces combined with those generated by isostatic readjustments due to denudation lead to old zones of crustal weakness getting reactivated and failing along old and new faults. This is the story seen all over the Indian peninsular regions, from the reactivation of Mesozoic faults in the Kutch region (Kutch earthquake 2001) to the Proterozoic central Indian Narmada rift region (Jabalpur earthquake 1997) to southern Maharashtra in the Koyna area and also eastwards near Latur (Killari earthquake 1993).

So far I have not seen any detailed justification why Koyna was chosen for this pioneer project over other regions at equal or greater risk from large earthquakes, for example the region in Gharwal Himalayas along the Main Central Thrust and the Main Boundary Thrust, major structures separating different Himalayan litho-tectonic terrains, or thrust faults along the Himalayan frontal range the Siwaliks which are close to large population centers like Chandigarh and Delhi.

Maybe its because the Koyna region is very well studied and at least one variable influencing the initiation of earthquakes in the Koyna region, the filling and draining of the reservoir and the stresses generated have been well monitored and modeled. These reservoir induced stresses are not nearly big enough to cause earthquakes on their own. They come into play only at a time when faults become critically stressed due to other geological forces, they are the piece of straw that broke the camel's back.

Direct monitoring the scientists are hoping will help understand how these other geological forces cause strain to gradually build up along the fault until breaking point.

Friday, September 3, 2010

On Cosmos and Culture 13.7 blog Marcelo Gleiser writes this about sponges:

Considering that sponges have been around for over 500 million years,
possibly even a billion years, many scientists believe they form the
base of the evolutionary branch in the tree of life that led to animals.
In other words, don’t think of humans as coming from monkeys; we, and
every other kind of critter out there, came from sponges, the cousins of
the porous yellowy objects you use to scrub yourself in the shower.

...we eukaryotes (non-bacterial life) trace our ancestry back to a
single-celled Most Recent Common Ancestor (MRCA) that inhabited the
planet some 1.5 to 2 billion years ago. This MRCA encoded all the core
eukaryotic “ideas”: how to make membranes with channels, how to regulate
gene expression, how to engage in meiotic sex. These ideas then moved
through evolutionary time into numerous radiations, with particular
ideas becoming expanded and elaborated, others degraded and lost, in
particular lineages.....

she explains further about animal ancestry:

..An ancestral creature with larval globular cells gave rise to two
lineages, one leading to modern sponges that have retained the
globular-cell idea, and the other leading to modern animals whose
“proto-neural” globular cells went on to acquire the capacity to
differentiate into full-fledged neurons.

Spot the difference between the two posts?

Maybe the author didn't mean it but the first gives the impression that sponges being the oldest of all animals gave rise to subsequent lineages of animals. But as clarified in the second post, sponges may be the oldest of all animals, but the rest of the animal kingdom did not evolve from them. Rather sponges and other animals share a common ancestor.

Evolutionary diversity forms through a branching process. Oldest simply means that the lineage that gave rise to modern sponges was the first to branch off from the root of the animal tree, root meaning the most recent common ancestor of all animals.

Oldest or "primitive" may also sometimes be taken to mean that the modern creature resembles the MRCA the most. But it certainly does not mean that sponges have stopped evolving since that early divergence. Modern sponges may have conserved certain ancestral traits, for example the globular cells sensitive to stimuli, but may also have acquired several new ones during their long evolutionary history.

Wednesday, September 1, 2010

Looking forward to some travel in the Himalayas later this year and I wanted to brush up on some details of the geology. I tend to always get confused about the relationship between the major structural discontinuities with major stratigraphic and physiographic divisions of the Himalayan orogen.

What I liked about it is that it covers the entire length and width of the orogen. The along strike variations in the major tectonic boundaries and stratigraphic units are clarified. Their local names are annotated properly along with the common names for the regions in which these geologic units fall. That is one of the major headaches of understanding Himalayan geology and this map does much to sort through the confusion.

Wednesday, August 25, 2010

In an effort to expand the higher education system, the Indian government in 2008 decided to open 8 additional branches of the Indian Institute of Technology. There was plenty of criticism of this move including a) is the decision being hastily implemented when the infrastructure is not yet ready? 2) are there enough new quality faculty available to teach? 3) would these new institutions become bogged down by the same byzantine bureaucracy and hierarchical stranglehold bedeviling older institutions?...

Its not that any or all of these concerns are invalid and indeed they may be playing themselves out in small or large measures on many of the new campuses of the IIT's. But sometimes I feel there is too much pessimism.

The Chronicle of Higher Education has a feel good story on the refreshingly positive experience of many U.S returned faculty who are now teaching at the new IIT campus in Ropar, Punjab, a small town near Chandigarh.

The administrators there worked hard at recruiting faculty, concentrating on young faculty and in fact manipulating the recruitment process to facilitate quick hiring, and then giving them considerable freedom in setting up syllabus and research labs. Here are some snippets:

Ropar has tapped alumni networks abroad and marketed its advantages as a flexible new player in a mostly hidebound system.....

.... So how did Ropar do it? To get the word out, administrators relied on their established network of IIT contacts and alumni, including holding events in the United States to explain the opportunities available at the new campuses in India.

Once they found a candidate they wanted, they figured out ways to cut through India's notorious red tape.

For example, Ropar's new hires often start in a "visiting position" to avoid the lengthy selection process involved in hiring permanent faculty members.

Then the institute works on converting them into permanent faculty members.

And some faculty and student comments:

"I can see a lot more flexibility and freedom here in terms of research and teaching," says Himanshu Tyagi, 31, a graduate of IIT Delhi, .....

New research "is taking off here," Mr. Gupta says. "So you can actually
set up your own lab and make an actual contribution, which is kind of
hard in the U.S."

"The faculty here are much younger than Delhi's, and they are ready to
experiment," says Ishan Chhabra, a third-year computer-science student.
"They are ready with bleeding-edge research, and they take it and expose
undergraduates to it. In an older institute, only Ph.D. students would
be introduced to it."

I think the "lets make a fresh start" and "making an impact" mentality among young faculty is helping along with some enlightened and sympathetic administrative decisions.

Off course there are always the occasional hazards:

In the car with a young trainee and her mother, Mr. Gupta was fumbling with the stick shift until the instructor proudly announced that his student was a "foreign returned" professor at the new Indian Institute of Technology down the road.

There was a brief silence. "Are you married?" the girl's mother inquired.

Monday, August 23, 2010

BLDGBLOG writes about research being done along the San Andreas Fault in the Carrizo plain, in an effort to understand historical seismicity along the fault. The paper has been published in the September issue of Geology. The story has been making news as results suggest that major earthquakes since the 1300's have been occurring at approximately century long intervals before the last big one in 1857....

Imagine a rogue, university-funded team of geologists researching
ever-lower levels of the earth, forcing themselves downward with
separating devices that pin open rocky wounds to split whole landmasses
along unanticipated faultlines. Using these tools—terrain deformation grenades gone linear—they create islands in the earth's crust, like walled castles of geology, carving out new blocks in the landscape.

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ABOUT THIS BLOG

I am a Sedimentary Geologist. On Rapid Uplift I write mostly about topics within the geosciences, but sometimes on biological evolution and environmental issues. I like to travel and in my free time I teach 12 year old kids soccer and rugby.